<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <link rel="stylesheet" href="rem.css">
</head>
<body>
    <div class="body-tip"></div>
    <div class="t t0">I'm px</div>
    <div class="t t1">I'm t1</div>
    <div class="t t2">I'm t2</div>
    <div class="t t3">I'm t3</div>
    <div class="p1"><div class="t t4">I'm t4</div></div>
    <div class="t t5">I'm t5</div>
    <div class="t t6">I'm t6</div>
    <script src="jquery.js"></script>
    <script>
        $(function() {
            $('div').each(function(i, ele) {
                var divEle = $(ele);
                var tipEle = $('<div class="tip">' +
                    '<span class="mr_20">width:' + divEle.width() + '</span>' +
                    '<span class="mr_20">height:' + divEle.height() + '</span>' +
                    '<span class="mr_20">fontsize:' + divEle.css('font-size') + '</span>' +
                    '</div>').css({'top': 0, 'left': divEle.width() + 10,});
                $(ele).append(tipEle);
            });
            $('.body-tip').text('font-size: ' + $('body').css('font-size'));
        });
    </script>
</body>
</html>